Lauren Davis

At Saturn's North pole sits a weather mystery: a giant hexagon formed by the path of a jet stream. It's a phenomenon that has remained largely unchanged for decades, at least, and scientists are trying to figure out why.

The Cassini spacecraft recently sent back images of Saturn's strange hexagon, which was last photographed 30 years ago by Voyager. So what is so unusual about it? In comparing the pictures now from the pictures 30 years ago, scientists have found that the shape of the hexagon has remained unchanged, making it an extremely long-lived weather pattern, perhaps akin to Jupiter's Great Red Spot.

Researchers are trying to determine what causes the weather pattern — which has a diameter more than twice as long as Earth's — how it gets and expels its energy, and how it maintains such a rigid shape. Fortunately, the improved images from Cassini and the fact that Saturn probably has a relatively simple weather model should help the researchers get a better understanding of the hexagon and how weather works on other planets.